1. Field of the Invention
The present invention relates generally to a digital playback device and a method and apparatus for modifying a digital audio signal. More specifically, the present invention relates a digital playback device and a method and apparatus for modifying a digital audio signal to enhance the listening experience of a user.
2. Description of Related Art
A large percentage of the population experiences some form of an auditory system disorder. For many people, the disorder can be extremely disturbing and can, in some instances, lead to additional disorders. One example of an often disturbing type of auditory system disorder is hyperacusis. Hyperacusis is an intolerance for external noises, even at lower levels. Another auditory system disorder, which is related to hyperacusis, is tinnitus. People with tinnitus perceive sounds that are not present in the external environment and/or that other people cannot generally hear. These sounds can include ringing in the ears, buzzing and humming background sounds, roaring or whistling noises in the ears.
Tinnitus can have a negative impact on work, family and social life and can lead to an inability to relax and disturbance of concentration and sleep patterns. Tinnitus can be caused by hearing loss resulting from exposure to loud noises, certain types of drug & medication, or middle ear infections. In some instances, tinnitus arises from a condition that requires medical or surgical intervention.
A large proportion of the population (around 15%), experience some degree of tinnitus and some reaction involving multiple areas of the brain. For a small proportion, around 1-2% of the general population, a secondary reaction which consists of a negative, self-reinforcing cycle is present involving the auditory cortex, the brain stem, the limbic and autonomic systems, leads to significant distress and disturbance. This reaction appears to involve neural rewiring as recently demonstrated with MRI and PET brain scanning.
Another common auditory disorder is hearing loss. Sufferers of this condition often find that their listening experience in many situations is significantly impaired, for example when listening to music.
Accordingly, a solution is needed to assist these individuals manage the effects of these auditory system disorders.